Millions of people including hundreds of thousands of schoolchildren are taking to the streets in 150 countries today for the largest climate protest in history.
The so-called 'Global Strike 4 Climate Change' rally started in Sydney this morning and is spreading west across the world to most of the planet's biggest cities including Hong Kong, Bangkok, Jakarta, Delhi, London and New York.
But in China - the world's most polluting nation - President Xi's government has banned the movement protesting in its cities.
In Australia today 300,000 people have taken part including more than 50,000 people in Sydney with Thor star Chris Hemsworth and his young daughter India among those who flooded the streets calling for governments and businesses to commit to a target of net zero carbon emissions by 2030.
But there were some arrests as scuffles broke out between a minority of activists and police.
Children carrying placards saying 'Time is almost up' and 'you will die of old age - I will die of climate change' are being let out of school to march for urgent action on climate change inspired by the protest movement led by young Swede Greta Thunberg.
In New York the city's Department of Education says all its 1.1million schoolchildren can skip class to participate in the strike if they had parental consent - without any fear of punishment.
Miss Thunberg, who has been nominated for a Nobel prize for her climate activism, will spearhead a rally at the United Nations headquarters in the city later.
Sydney: Children chanting for change march through Australia's largest city today as the 'Global Strike 4 Climate Change' began
In Australia today 300,000 people have taken part including more than 50,000 people in Sydney with Thor star Chris Hemsworth and his young daughter India among those who flooded the streets
Sydney: A protester clashes with police during the climate rally in Sydney on Friday before he was arrested and removed from the area
Bangkok: Marchers in Thailand decided to block the roads outside the Ministry of Natural Resources and Environment as they demanded action
Hong Kong: Protesters carrying coffins and placards accusing governments of 'ecocide' march through Hong Kong's famous harbour
Indonesia: Youths walk with signs through the main road during a Global Climate Strike rally as smog covers the city due to the forest fires in Palangka Raya, Central Kalimantan province
As the sea of people made their way through the city, some school students on scooters could be seen heading in the opposite direction, while there was some fighting between protesters and police.
However, there were hundreds of young people proving their dedication to the cause as they carried artistic placards they had made the night before, which read: 'Time is almost up' and 'There is no Planet B'.
Others could be seen scribbling their signs on old pieces of cardboard on the footpath as they waited for the event to begin.
One 14-year-old girl Daily Mail Australia spoke to had taken a two hour bus from the Central Coast to make it to the event and said: 'I'm here because I'm afraid for my future. I don't want to have kids and them to face the same problem'.
Britons joining the climate strikes can expect a day of unseasonably warm weather on Friday as they call on businesses and politicians to cut emissions.
Children and young people are preparing to walk out of lessons and lectures, with hundreds of thousands of workers expected to join them.
The protests are part of a snowballing movement sparked by teenage activist Greta Thunberg's school strikes outside the Swedish parliament.
It comes ahead of a climate action summit in New York convened by UN secretary general Antonio Guterres to urge countries to up their climate efforts.
Much steeper measures are needed across the globe to prevent temperature rises of more than 1.5C (2.7F) or 2C (3.6F) to avoid the worst impacts of climate change.
Brisbane: Millions of people from across the globe are expected to walk out of work and school as part of 'Strike 4 Climate Action' which will be held in 150 countries on September 20
In Australia there were hundreds of young people proving their dedication to the cause as they carried artistic placards they had made the night before, which read: 'Time is almost up' and 'There is no Planet B'sonos sonos One (Gen 2)